There are some interesting technological developments around fuel efficiency and minimizing the "sonic boom" that's felt on the ground. Neither of those killed Concorde though, because the entire idea of Concorde turned out to be incredibly faulty. MOST people weren't in such a hurry to get from point A to point B that they'd pay 5x-10x a normal business/first class ticket to cut a trip down by 50% or so. The intended 100+ units to be built and sold turned out to be a fantasy, airlines weren't interested.
Now consider what's changed: Back when Concorde was new, airline security was perfunctory and brief, so the time spent in the airport was a fraction of total travel time. Today that represents potentially 2+ hours of your travel time that can't be omitted. For much of Concorde's life the modern internet wasn't a thing, or at least mature; every business traveler didn't have the ability to have a conference call IN MID FLIGHT. Today that's routine.
So what's the hurry exactly? Sure some people might have a need or desire, but the planned jet holds 64 people who are going to have to pay through the nose to make it profitable for an airline. Who are these people who wouldn't rather take a sleeping pill or futz around on their laptop instead?
tl;dr Supersonic civil aviation is an ECONOMIC problem, not a technological one, and the economics haven't changed.
Now consider what's changed: Back when Concorde was new, airline security was perfunctory and brief, so the time spent in the airport was a fraction of total travel time. Today that represents potentially 2+ hours of your travel time that can't be omitted. For much of Concorde's life the modern internet wasn't a thing, or at least mature; every business traveler didn't have the ability to have a conference call IN MID FLIGHT. Today that's routine.
So what's the hurry exactly? Sure some people might have a need or desire, but the planned jet holds 64 people who are going to have to pay through the nose to make it profitable for an airline. Who are these people who wouldn't rather take a sleeping pill or futz around on their laptop instead?
tl;dr Supersonic civil aviation is an ECONOMIC problem, not a technological one, and the economics haven't changed.